Fire acrobats perform in front of the Bulgarian National Theatre, with lights turned off, as part of the Earth Hour in Sofia on March 23, 2013. Millions of people were expected to switch off their lights for Earth Hour on March 23 in a global effort to raise awareness about climate change that was even to be monitored from space. less

Fire acrobats perform in front of the Bulgarian National Theatre, with lights turned off, as part of the Earth Hour in Sofia on March 23, 2013. Millions of people were expected to switch off their lights for ... more

Muslim women light candles during the "EarthHour" in Jakarta, Indonesia, Saturday, March 23, 2013. Hundreds of people gathered in Jakarta Friday to observe the global event that encourages people to turn off their lights for 60 minutes. less

Muslim women light candles during the "EarthHour" in Jakarta, Indonesia, Saturday, March 23, 2013. Hundreds of people gathered in Jakarta Friday to observe the global event that encourages people to turn off ... more

The Chillon Castle is seen with lights off on the edge of Lake Geneva near Montreux, taking part of the Earth Hour on March 23, 2013. Millions of people were expected to switch off their lights for Earth Hour in a global effort to raise awareness about climate change. Since it began in Sydney in 2007, Earth Hour has grown to become what environmental group WWF says is the world's largest demonstration of support for action on carbon pollution. less

The Chillon Castle is seen with lights off on the edge of Lake Geneva near Montreux, taking part of the Earth Hour on March 23, 2013. Millions of people were expected to switch off their lights for Earth Hour ... more

Photo: FABRICE COFFRINI, AFP/Getty Images

The Chillon Castle is seen with lights off on the edge of Lake... Photo-4368454.58966 - Houston Chronicle

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People participate in Dance 2 Power Earth Hour at the Marina Floating Platform on March 23, 2013 in Singapore. Kinetic energy generated from footsteps are converted to electricity which is stored and used for the outdoor film screening. Earth hour began in Australia in 2007 and is now celebrated in over 150 countries around the world. less

People participate in Dance 2 Power Earth Hour at the Marina Floating Platform on March 23, 2013 in Singapore. Kinetic energy generated from footsteps are converted to electricity which is stored and used for ... more

Photo: Suhaimi Abdullah, Getty Images

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Taboola Gallery Frame Item-85307.58966 - Houston Chronicle

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The Elizabeth Tower, which houses Big Ben at the Houses of Parliament in London, illuminated, after the lights were turned off to mark Earth Hour 2013, Saturday March 23, 2013. Earth Hour was marked worldwide at 8.30 p.m. local time and is a global call to turn off lights for 60 minutes in a bid to highlight the global climate change. Metalwork at left is the London Eye. less

The Elizabeth Tower, which houses Big Ben at the Houses of Parliament in London, illuminated, after the lights were turned off to mark Earth Hour 2013, Saturday March 23, 2013. Earth Hour was marked worldwide ... more

Combo picture shows the Eiffel tower is seen before and after submerging into darkness at 8:30 pm (local time) as part of the Earth Hour switch-off on March 23, 2013 in Paris. Organisers expect hundreds of millions of people across more than 150 countries to turn off their lights for 60 minutes on Saturday night -- at 8:30 pm local time -- in a symbolic show of support for the planet. While more than 150 countries joined in last year's event, the movement has spread even further afield this year, with Palestine, Tunisia, Suriname and Rwanda among a host of newcomers pledging to take part. less

Combo picture shows the Eiffel tower is seen before and after submerging into darkness at 8:30 pm (local time) as part of the Earth Hour switch-off on March 23, 2013 in Paris. Organisers expect hundreds of ... more

Photo: BERTRAND LANGLOIS, AFP/Getty Images

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This picture shows people standing next to candles arranged to read "Tunisia" in the Habib Bourguiba avenue after submerging into darkness as part of the Earth Hour switch-off in Tunis on March 23, 2013. Organisers expect hundreds of millions of people across more than 150 countries to turn off their lights for 60 minutes on Saturday night -- at 8:30 pm local time -- in a symbolic show of support for the planet. While more than 150 countries joined in last year's event, the movement has spread even further afield this year, with Palestine, Tunisia, Suriname and Rwanda among a host of newcomers pledging to take part. less

This picture shows people standing next to candles arranged to read "Tunisia" in the Habib Bourguiba avenue after submerging into darkness as part of the Earth Hour switch-off in Tunis on March 23, 2013. ... more

Photo: SAFA LAAMIRI, AFP/Getty Images

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The Hungarian Parliament is pictured in downtown Budapest on March 23, 2013 the Earth hour when the lights are turned off for an hour to save energy. Millions of people were expected to switch off their lights for Earth Hour in a global effort to raise awareness about climate change. Since it began in Sydney in 2007, Earth Hour has grown to become what environmental group WWF says is the world's largest demonstration of support for action on carbon pollution. less

The Hungarian Parliament is pictured in downtown Budapest on March 23, 2013 the Earth hour when the lights are turned off for an hour to save energy. Millions of people were expected to switch off their lights ... more

The Parthenon temple stands atop the Acropolis hill after turning off lights, to mark the annual Earth Hour in Athens, Saturday March 23, 2013. In Greece, floodlights in several monuments and public buildings were switched off for one hour at 8:30 p.m. local time. Thousands of businesses and municipalities also dimmed their lights. less

The Parthenon temple stands atop the Acropolis hill after turning off lights, to mark the annual Earth Hour in Athens, Saturday March 23, 2013. In Greece, floodlights in several monuments and public buildings ... more

The lights are turned off at the Kremlin during the worldwide Earth Hour in Moscow, Russia, Saturday, March 23, 2013. The Kremlin is participating in the Earth Hour for the first time. During Earth Hour people around the world turn off the electric lights for an hour from 8.30pm to focus on climate problems. less

The lights are turned off at the Kremlin during the worldwide Earth Hour in Moscow, Russia, Saturday, March 23, 2013. The Kremlin is participating in the Earth Hour for the first time. During Earth Hour people ... more

Photo: Alexander Zemlianichenko Jr, Associated Press

The lights are turned off at the Kremlin during the worldwide Earth... Photo-4368461.58966 - Houston Chronicle

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A general view of the Indian Presidential Palace with lights switched off during an Earth Hour event in New Delhi on March 23, 2013. Millions of people were expected to switch off their lights for Earth Hour on March 23, in a global effort to raise awareness about climate change. Since it began in Sydney in 2007, Earth Hour has grown to become what environmental group WWF says is the world's largest demonstration of support for action on carbon pollution. less

A general view of the Indian Presidential Palace with lights switched off during an Earth Hour event in New Delhi on March 23, 2013. Millions of people were expected to switch off their lights for Earth Hour ... more

Photo: RAVEENDRAN, AFP/Getty Images

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This general shot shows buildings from Manila's financial district after the lights were turned off to mark Earth Hour in Manila on March 23, 2013. Millions of people were expected to switch off their lights for Earth Hour on March 23, in a global effort to raise awareness about climate change. Since it began in Sydney in 2007, Earth Hour has grown to become what environmental group WWF says is the world's largest demonstration of support for action on carbon pollution. less

This general shot shows buildings from Manila's financial district after the lights were turned off to mark Earth Hour in Manila on March 23, 2013. Millions of people were expected to switch off their lights ... more

People light candles as they take part in an event to promote "Earth Hour" in the financial district of Shanghai on March 23, 2013. Iconic landmarks and skylines were plunged into darkness as the "Earth Hour" switch-off of lights around the world got under way including China's commercial hub of Shanghai to raise awareness of climate change. less

People light candles as they take part in an event to promote "Earth Hour" in the financial district of Shanghai on March 23, 2013. Iconic landmarks and skylines were plunged into darkness as the "Earth Hour" ... more

Photo: PETER PARKS, AFP/Getty Images

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The Taipei 101 Building is seen darkened during the Earth Hour in Taipei, Taiwan, Saturday, March 23, 2013. Organised by the World Wide Fund for Nature, earth hour is observed every year to create awareness about conservation of energy and climate change. Around the world, people and organisations will be turning their lights off from 8:30 to 9:30 pm local time. less

The Taipei 101 Building is seen darkened during the Earth Hour in Taipei, Taiwan, Saturday, March 23, 2013. Organised by the World Wide Fund for Nature, earth hour is observed every year to create awareness ... more

Photo: Chiang Ying-ying, Associated Press

The Taipei 101 Building is seen darkened during the Earth Hour in... Photo-4368465.58966 - Houston Chronicle